getContentLength() returning -1

Android url connection getContentLength() returning negative value (-1) ?

SOLUTION
(ÇÖZÜM)

add this line 
(Bu satırı ekle)

urlConnection.setRequestProperty("Accept-Encoding","identiy");
.
.
.
as it's shown below
(aşağıda gösterildiği gibi)

HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestProperty("Accept-Encoding","identiy"); // <--- Add this
int length = urlConnection.getContentLength();